General Description
The MAX6806/MAX6807/MAX6808 precision voltage
detectors are ideal for accurate monitoring of power
supplies in digital systems. They provide circuit reliabili-
ty and reduce total cost by eliminating external compo-
nents and adjustments.
The MAX6806/MAX6807/MAX6808 assert a reset signal
whenever the supply voltage (VCC) falls below the factory-
preset, ±2% accurate threshold. Internal hysteresis
ensures stable switching. The MAX6806/MAX6807/
MAX6808 are available in 4.6V and 2.6V thresholds (2.3V
is also available for the MAX6806 only). The MAX6806 fea-
tures an active-low, push-pull RESET output; the MAX6807
features an active-high, push-pull RESET output; and the
MAX6808 features an active-low, open-drain RESET out-
put. RESET is valid for VCC down to 1V (MAX6806/
MAX6808), and RESET (MAX6807) is guaranteed for VCC
down to 1.2V.
The MAX6806/MAX6807/MAX6808 are available in
3-pin SC70, 3-pin SOT23, 8-pin µMAX, 8-pin SO, and 4-
pin SOT143 packages. The SOT143 package includes
a manual-reset input.
Applications
Computers Automotive
Controllers Bar-Code Scanners
Intelligent Instruments
Critical µP and µC Power Monitoring
Portable/Battery-Powered Equipment
Features
♦Preset Reset Thresholds: 4.6V and 2.6V
(2.3V also available for MAX6806 only)
♦±2% Accurate Reset Thresholds
♦Reset Output Available in Active-Low (MAX6806),
Active-High (MAX6807), and Open-Drain
(MAX6808) Versions
♦Immune to Power-Supply Transients
♦RESET Valid to VCC = 1.0V (MAX6806/MAX6808)
♦35µA Supply Current
♦No External Components
♦Manual Reset Available with 4-Pin SOT143
Package
♦Miniature 3-Pin SC70, 3-Pin SOT23, and 4-Pin
SOT143 Packages
♦8 Lead µMAX and 8 Lead SO Packages are Pin
Compatible with the MC33064/MC33164/
MC34064/MC34164
MAX6806/MAX6807/MAX6808
Voltage Detectors
________________________________________________________________ Maxim Integrated Products 1
19-1421; Rev 2; 4/01
Ordering Information
Selector Guide and Pin Configurations appear at end of data
sheet.
* SOT23, SOT143, and SC70s are available in tape-and-reel
only, 2500 piece minimum order quantity.
Note: Insert the desired number from the Selector Guide into the
blank to complete the part number. Also see Selector Guide for
top mark for SOT23
PART TEMP. RANGE PIN-PACKAGE
MAX6806XR_ _ -T -40°C to +85°C 3 SC70
MAX6806UR_ _ -T -40°C to +85°C 3 SOT23
MAX6806US_ _ -T -40°C to +85°C 4 SOT143
MAX6806UA_ _ -40°C to +85°C 8 µMAX
MAX6806SA_ _ -40°C to +85°C 8 SO
MAX6807XR_ _ -T -40°C to +85°C 3 SC70
MAX6807UR_ _ -T -40°C to +85°C 3 SOT23
MAX6807US_ _ -T -40°C to +85°C 4 SOT143
MAX6807UA_ _ -40°C to +85°C 8 µMAX
MAX6807SA_ _ -40°C to +85°C 8 SO
MAX6808XR_ _ -T -40°C to +85°C 3 SC70
MAX6808UR_ _ -T -40°C to +85°C 3 SOT23
MAX6808US_ _ -T -40°C to +85°C 4 SOT143
MAX6808UA_ _ -40°C to +85°C 8 µMAX
MAX6808SA_ _ -40°C to +85°C 8 SO
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Typical Operating Circuit
MAX6806
MAX6807
MAX6808
VCC
VCC VCC
GND GND
µP
(RESET)/RESET RESET
INPUT
( ) ARE FOR MAX6807
MAX6806/MAX6807/MAX6808
Voltage Detectors
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC = +5V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Note1: All devices are 100% production tested at TA = +25°C, and are guaranteed by design for TA= TMIN to TMAX, as specified.
Note 2: RESET output for MAX6806/MAX6808, RESET output for MAX6807.
VCC to GND ..........................................................-0.3V to +6.0V
RESET, RESET to GND
(MAX6806/MAX6807) ................................-0.3V to (VCC + 0.3V)
RESET to GND (MAX6808)...................................-0.3V to + 6.0V
MR to GND (SOT143 package only) ....................-0.3V to + 6.0V
Input Current, VCC ...........................................................±20mA
Output Current, RESET, RESET .......................................±20mA
Rate of Rise, VCC ...........................................................100V/µs
Continuous Power Dissipation (TA= +70°C)
SOT23, SOT143 (derate 4mW/°C above +70°C) .........320mW
SC70 (derate 2.17mW/°C above +70°C) .....................174mW
µMAX (derate 4.5mW/°C above +70°C) ......................362mW
SO (derate 5.9mW/°C above +70°C) ...........................471mW
Operating Temperature Range ..........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10s) .................................+300°C
VCC = +3.6V, no load
VCC > VTH+
TA= -40°C to +85°C
TA= 0°C to +70°C
VCC falling at 1mV/µs
ISINK = 1.0mA, VCC = 2.0V
ISINK = 3.2mA, VCC = 5.0V
ISOURCE = 400µA, VCC = 2.0V
ISINK = 20µA, VCC = 1.0V
TA= +25°C,
VCC falling
VCC = +5.5V, no load
ISOURCE = 20µA, VCC = 1.2V
CONDITIONS
V
0.7VCC
VIH
MR Input Threshold 0.6VIL
kΩ40 80 120RMR
MR Pull-Down Resistance
ppm/°C30Reset Threshold Tempco
µs30VCC to Reset Delay (Note 2)
0.4VOL
RESET Output Voltage
(MAX6807) V
0.8VCC
VOH
0.8VCC
35 60
V
1.2 5.5
VCC
1.0 5.5
Supply Voltage Range
VOL 0.4
0.3
2.254 2.30 2.346
VTH-
Reset Threshold
µA
50 80
ICC
Supply Current
4.508 4.60 4.692
3.136 3.20 3.264 V
2.548 2.60 2.652
UNITSMIN TYP MAXSYMBOLPARAMETER
MAX680_ _ _46
MAX680_ _ _32
MAX680_ _ _26
VOH ISOURCE = 2.0mA, VCC = 5.0V
(MAX6806 only)
RESET Output Voltage
(MAX6806/MAX6808) V
0.8VCC
VCC = 5.5V, RESET deasserted
(MAX6808 only) µA1IOH
RESET Output Leakage Current
TA= +25°C, Figure 2 V
0.02 0.03
VTH- VTH-
VHYST
Reset Threshold Hysteresis
MAX680_ _ _23
MAX6806/MAX6807/MAX6808
Voltage Detectors
_______________________________________________________________________________________ 3
Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
0
10
5
20
15
30
25
35
45
40
50
-60 -30 0 30 60 12090
SUPPLY CURRENT vs. TEMPERATURE
MAX6806/7/8-01
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
VCC = 5.0V
VCC = 3.3V
VCC = 1.8V
VCC = 1.0V
25
29
27
33
31
35
37
43
41
39
45
-60 -30-15 0-45 15 30 45 7560 90 105 120135
POWER-DOWN RESET DELAY
vs. TEMPERATURE
MAX6806/7/8toc02
TEMPERATURE (°C)
RESET DELAY (µs)
VOD = VTH- - VCC = 100mV
VCC FALLING AT 1mV/µS
4
6
5
7
9
8
11
10
12
-60 -30 0 30 60 12090
POWER-UP RESET DELAY vs. TEMPERATURE
MAX6806/7/8-03
TEMPERATURE (°C)
DELAY TIME (µs)
VOD = VCC - VTH+
VOD = 50mV
VOD = 200mV
VOD = 100mV
0.9900
0.9940
0.9920
0.9980
0.9960
1.0020
1.0000
1.0040
1.0080
1.0060
1.0100
-40 -15 0-30 15 30 6045 8575
NORMALIZED RESET THRESHOLD
vs. TEMPERATURE
MAX6806/7/8-04
TEMPERATURE (°C)
NORMALIZED RESET THRESHOLD
VCC RISING (VTH+)
VCC FALLING (VTH-)
1
Active-Low Reset Output (MAX6806/MAX6808). RESET remains low while VCC
is below the reset-threshold voltage or while MR is held high.
Active-High Reset Output (MAX6807). RESET remains high while VCC is below
the reset-threshold voltage or while MR is held high.
2Ground
3Supply Voltage Input
—Active-High Manual Reset Input. Internal 80kΩresistor to GND.
SOT23/SC70
FUNCTION
Pin Description
RESET
RESET
GND
VCC
MR
NAME
1
4
3
2
SOT143
PIN
N.C.—Not Internally Connected—3, 5–8
1
4
2
—
µMAX/SO
MAX6806/MAX6807/MAX6808
Voltage Detectors
4 _______________________________________________________________________________________
_______________Detailed Description
Reset Output
The MAX6806 voltage detector features an active-low,
push-pull RESET output, while the MAX6807 features
an active-high, push-pull RESET output. Unlike micro-
processor (µP) supervisory circuits that offer a reset
timeout period, the MAX6806 and MAX6807 RESET
goes high and RESET goes low virtually immediately
once VCC exceeds the reset threshold. If a brownout
occurs (VCC falls below the reset threshold), RESET
goes low and RESET goes high. RESET is guaranteed
to be a logic low for VCC ≥1V and RESET is guaran-
teed to be a logic high for VCC ≥1.2V.
The MAX6808 features an active-low, open-drain RESET
output. The output sinks current when VCC falls below
the reset threshold. Connect a pull-up resistor from
RESET to any supply voltage up to 6V (Figure 1). Select
a resistor value large enough to provide a logic low and
small enough to provide a logic high while supplying all
input and leakage currents connected to the RESET
line. A 100kΩresistor is sufficient in applications driving
high-impedance loads.
The manual reset input (MR, 4-pin SOT143 package)
can also initiate a reset (see Manual Reset Input sec-
tion).
Manual Reset Input
Many applications require manual-reset capabilities,
allowing an operator, a test technician, or external logic
circuitry to initiate a reset. A logic high on MR asserts a
reset and remains asserted while MR is high. This input
has an 80kΩpull-down resistor, so the input may be left
unconnected if not used. Connect a normally open
momentary switch from MR to VCC to create a manual-
reset function. If MR is driven from long cables or if the
device is used in a noisy environment, connecting a
0.1µF capacitor from MR to ground provides noise
immunity.
Hysteresis
The MAX6806/MAX6807/MAX6808 feature internal hys-
teresis that creates two trip points: one for the rising
supply voltage and one for the falling supply voltage
(Figure 2). The hysteresis prevents the output from oscil-
lating (chattering) when VCC is near the reset threshold.
Reset Threshold Accuracy
The MAX6806/MAX6807/MAX6808 are ideal for sys-
tems using a 5V ±5%, 3V ±5%, or 2.5V ±5% power
supply with ICs specified for 5V ±10%, 3V ±10%, or
2.5V ±10%, respectively. The reset is guaranteed to
assert after the power supply falls out of regulation, but
before power drops below the minimum specified oper-
ating voltage range for the system ICs.
MAX6808
VCC VCC
GND
+3.3V
GND
+5.0V
100kΩ5V SYSTEM
RESET
Figure 1. The MAX6808 open-drain
RESET
output allows use
with multiple supplies.
VTH+
HYST
RESET
(MAX6806/MAX6808)
RESET
(MAX6807)
VHYST = VTH+ - VTH-
VOH
VOL
VOH
VOL
VTH-
Figure 2. Input and Output Waveforms with VCC Varied
Applications Information
Negative-Going VCC Transients
In addition to asserting a reset signal during power-up,
power-down, and brown-out conditions, the MAX6806/
MAX6807/MAX6808 are immune to short-duration, neg-
ative-going VCC transients.
Figure 3 displays typical transient durations vs. reset-
comparator overdrive for which the MAX6806/MAX6807/
MAX6808 do not generate a reset pulse. The graph was
generated using a negative-going pulse applied to VCC,
starting 0.5V above the actual reset threshold and end-
ing below it by the magnitude indicated (reset-compara-
tor overdrive). The graph indicates the maximum pulse
width a negative-going VCC transient can have without
causing a reset pulse. As the magnitude of the transient
increases (goes further below the reset threshold), the
maximum allowable pulse width decreases. A 0.1µF
capacitor mounted as close as possible to VCC pro-
vides additional transient immunity.
Ensuring a Valid Reset Output Down to
VCC = Ground
When VCC falls below 1V, the MAX6806/MAX6808
RESET output no longer sinks current—it becomes an
open circuit. Therefore, high-impedance CMOS logic
inputs connected to RESET can drift to undetermined
voltages. This presents no problem in most applica-
tions, since most circuitry is inoperative when VCC is
below 1V. In applications where RESET must be valid
down to ground, add a pull-down resistor to RESET so
any stray leakage currents flow to ground, holding
RESET low (Figure 4). Select R1 to be large enough not
to load RESET and small enough to pull RESET to
ground. For most applications, 100kΩwill not load
RESET and will pull RESET to ground. Similarly, if
RESET (MAX6807) must be valid below 1.2V, add a
pull-up resistor to RESET.
MAX6806/MAX6807/MAX6808
Voltage Detectors
_______________________________________________________________________________________ 5
80
70
20
10 100 1000
40
30
50
60
RESET COMPARATOR OVERDRIVE, VTH- - VCC (mV)
MAXIMUM TRANSIENT DURATION (µs)
TA = +25°C
MAX680 46
Figure 3. Maximum Transient Duration without Causing a
Reset Pulse vs. Reset Comparator Overdrive
MAX6806 MAX6807
VCC VCC
GND GND
RESET RESET
R1
100kΩ
R1
100kΩ
Figure 4.
RESET
/ RESET Valid to VCC = Ground Circuit
MAX6806/MAX6807/MAX6808
Interfacing to µPs with
Bidirectional Reset Pins
µPs with bidirectional reset pins (such as the Motorola
68HC11 series) can contend with push-pull RESET out-
puts, resulting in indeterminate logic levels. Use the
MAX6808 with the open-drain RESET when interfacing
to this type of controller.
Voltage Detectors
6 _______________________________________________________________________________________
MAX6808
VCC
VCC
VCC
GND GND
4.7kΩµP
RESET RESET
Figure 5. Interfacing to µPs with Bidirectional Reset I/O
Selector Guide
PART RESET OUTPUT TOP MARK CODE NOMINAL VTH (V)
MAX6806SA46 —4.6
MAX6806SA26 —2.6
MAX6806SA23 —2.3
MAX6806UA46 —4.6
MAX6806UA26 —2.6
MAX6806UA23 —2.3
MAX6806UR46-T FZDP 4.6
MAX6806UR26-T FZDQ 2.6
MAX6806UR23-T FZDR 2.3
MAX6806US46-T KABT 4.6
MAX6806US26-T KABU 2.6
MAX6806US23-T KABV 2.3
MAX6806XR46-T AAA 4.6
MAX6806XR26-T AAB 2.6
MAX6806XR23-T
Active-Low, Push-Pull
AAC 2.3
MAX6806/MAX6807/MAX6808
Voltage Detectors
_______________________________________________________________________________________ 7
Other voltage thresholds may be available. Contact factory for availability.
Selector Guide (continued)
PART RESET OUTPUT TOP MARK CODE NOMINAL VTH (V)
MAX6807SA46 —4.6
MAX6807SA26 —2.6
MAX6807UA46 —4.6
MAX6807UA26 —2.6
MAX6807UR46-T FZDS 4.6
MAX6807UR26-T FZDT 2.6
MAX6807US46-T KABW 4.6
MAX6807US26-T KABX 2.6
MAX6807XR46-T AAD 4.6
MAX6807XR26-T
Active-High, Push-Pull
AAE 2.6
MAX6808SA46 —4.6
MAX6808SA32 —3.2
MAX6808SA26 —2.6
MAX6808UA46 —4.6
MAX6808UA32 —3.2
MAX6808UA26 —2.6
MAX6808UR46-T FZDU 4.6
MAX6808UR32-T FZFL 3.2
MAX6808UR26-T FZDV 2.6
MAX6808US46-T KABY 4.6
MAX6808US32-T KACC 3.2
MAX6808US26-T KABZ 2.6
MAX6808XR46-T AAF 4.6
MAX6808XR32-T ACD 3.2
MAX6808XR26-T
Active-Low, Open-Drain
AAG 2.6
MAX6806/MAX6807/MAX6808
Voltage Detectors
8 _______________________________________________________________________________________
___________________Chip Information
TRANSISTOR COUNT: 72
Pin Configurations
TOP VIEW
GND
1
3VCC
(RESET)/RESET
MAX6806
MAX6807
MAX6808
SOT23/SC70
2
( ) ARE FOR MAX6807
1
2
4
3
GND
VCC
MR
(RESET)/RESET
MAX6806
MAX6807
MAX6808
SOT143
MAX6806
MAX6807
MAX6808
µMAX/SO
8N.C.
5N.C.
4GND
1(RESET)/RESET
2VCC
3N.C. 6N.C.
7N.C.
MAX6806/MAX6807/MAX6808
Voltage Detectors
_______________________________________________________________________________________ 9
Package Information
SC70, 3L.EPS
MAX6806/MAX6807/MAX6808
Voltage Detectors
10 ______________________________________________________________________________________
Package Information (continued)
SOTPO3L.EPS
MAX6806/MAX6807/MAX6808
Voltage Detectors
______________________________________________________________________________________ 11
Package Information (continued)
SOT1434.EPS
MAX6806/MAX6807/MAX6808
Voltage Detectors
12 ______________________________________________________________________________________
Package Information (continued)
8LUMAXD.EPS
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________13
© 2001 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Package Information (continued)
MAX6806/MAX6807/MAX6808
Voltage Detectors
SOICN.EPS
